Bubble-size distributions and flow fields in bubble columns
Bubble-size distributions and flow fields in bubble columns
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DOI：
10.1002/aic.690481103
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发表时间：
2002-11-01
期刊：
影响因子：
3.7
通讯作者：
Mewes, D
中科院分区：
文献类型：
--
作者：
Lehr, F;Millies, M;Mewes, D
对鼓泡塔内的气泡尺寸分布和流场进行了数值计算。粒子数平衡被简化为平均气泡体积的平衡方程。所开发的模型基于物理原理预测气泡破裂和聚结的速率。采用欧拉-欧拉方法对圆柱形截面鼓泡塔内的流场进行了数值计算。新推导出的平均气泡体积的平衡方程被实施到商业CFD代码。对于高表观气速，平衡方程的解主要产生两个部分：一个部分具有小气泡直径，另一个部分具有大气泡直径。除了液相之外，两者都被认为是假连续相。计算的流场的特点是几个大尺度涡。气体和液体的局部体积分数是局部不均匀的，并且高度依赖于时间。时均流场是轴对称的、定常的。计算出的体积分数，速度和气泡尺寸分布同意与现有的和以前发表的实验结果鼓泡塔直径达0.3米。
Bubble-size distributions and flow fields in bubble columns are calculated numerically. The population balance is simplified and reduced to a balance equation for the average bubble volume. Models developed predict the rate of bubble breakup and coalescence based on physical principles. The flow fields are numerically calculated for bubble columns with cylindrical cross sections using the Euler-Euler method. The newly derived balance equations for the average bubble volumes are implemented into a commercial CFD code. The solutions of the balance equation for high superficial gas velocities result mainly in two fractions: one for the fraction with small and the other for the fraction with large bubble diameters. Both are considered pseudocontinuous phases, in addition to the liquid phase. The calculated flow fields are characterized by several large-scale vortices. The local volume fractions of gas and liquid are locally inhomogeneous and highly time-dependent. The time-averaged flow field is axisymmetric and stationary. The calculated volume fractions, velocities, and bubble-size distributions agree well with existing and previously published experimental results for bubble columns up to 0.3 m in diameter.